The production of copolymers of cellulose and starch with vinyl monomers has been studied widely in the past years. The interest in obtaining copolymers of these abundant natural materials with vinyl monomers lies mainly in the production of fibers and synthetic papers with improved properties. Copolymers of these materials with methyl methacrylate, acrylonitrile, acrylic acid and methacrylic acid have been used in ion exchangers, as dispersing agents and as paper additives.
The patent literature reveals many processes for the production of cellulose copolymers using gamma radiation, e.g. U.S. Pat. No. 3,561,933 and by oxidizing cellulose, e.g. U.S. Pat. No. 3,095,391. All of the processes differ in the method of producing the active species on cellulose or starch, but are alike in that they are heterogenous processes that produce graft copolymers.
A slightly different procedure for synthesizing cellulose copolymers has been to make a soluble cellulose ester and utilizing this as a chain transfer agent. Different types of reactions have also been attempted, e.g. U.S. Pat. No. 3,455,853.